Device for determining at least one parameter of a flowing gas-liquid mixture or using a flow rectifier as a condensation trap or method for condensing a liquid

ABSTRACT

A device and method for determining at least one parameter of a flowing gas-liquid mixture, including parameters of the intake air of internal combustion engines, uses a condensation trap to protect a measuring element from back flowing liquids, downstream from the measuring element.

FIELD OF THE INVENTION

The present invention relates to a device for determining at least oneparameter of a flowing gas-liquid mixture, to the use of a flowstraightener as a condensation trap, and/or to a method for condensing aliquid.

BACKGROUND INFORMATION

A device is discussed in European Patent Application No. 0 458 998 fordetermining the intake-air volume of an internal combustion engine, theintake-air flowing around a measuring element in a main flow direction.As characterized, a flow straightener having a plurality of openings ispresent upstream from the measuring element. Downstream from themeasuring element is a grating for protecting the measuring element frommechanical influences, such as, for example, from direct hand contact. Amesh aperture of the grating is specially produced in a wide-meshedmanner. While the device is in operation, oil drops or oil vapor can,for example, flow in the air against the main flow direction andcontaminate the measuring element, which may significantly worsen themeasuring properties of the measuring element. The backflow of liquidsmay result from pulsating flows or from a turbo-charger running on inthe stopping phase. The inner surface of the protective grating having aspecial wide-meshed design, may not be sufficient as a condensationsurface for the liquid.

A device is discussed in German Published Patent Application No. 196 47081 for determining the volume of a flowing medium, in which a gridpossesses flow openings having, at least regionally, different flowcross sections. However, the grid is situated upstream from themeasuring element.

SUMMARY OF THE INVENTION

In contrast, the exemplary device according to the present invention,the use of an exemplary flow straightener according to the presentinvention as a condensation trap, and/or the exemplary method forcondensing a liquid according the present invention may have theadvantage that a measuring element is protected from contamination in asimple manner.

An element having an enlarged inner surface downstream from themeasuring element may be used as a condensation trap in a simple,mechanical manner.

A flow straightener may also be used as the condensation trap by aninexpensive and simple modification.

An exemplary embodiment includes integrating the condensation trap in atubular member, which may result in a reduction in production costs andin the number of parts to be assembled.

A flow straightener may also be used upstream from the measuring elementto provide good flow conditions.

To effectively protect the measuring element from liquid and solidparticles, it may be advantageous to integrate a protective grid atleast regionally in the flow straightener upstream from the measuringelement.

A protective half-pipe may also be used to shield an opening of atubular member from liquid and solid particles, so that a protectivefunction of the measuring element may be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first exemplary device according to the present inventionfor determining at least one parameter of a flowing gas-liquid mixture.

FIG. 2 shows another exemplary device according to the presentinvention.

FIG. 3 shows still another exemplary device according to the presentinvention.

FIG. 4 shows yet another exemplary device according to the presentinvention.

DETAILED DESCRIPTION

FIG. 1 shows a partial sectional view of a first exemplary embodiment ofa device 50 for determining at least one parameter of a gas-liquidmixture flowing in a line, such as an intake-air volume of an internalcombustion engine.

Reference numeral 1 designates a line that may form a direct segment ofthe intake pipe of the internal combustion engine or that is anindependent component part that can be connected to the intake pipe ofthe internal combustion engine. In either case, line 1 is downstreamfrom an air filter (not shown) on its “clean room” side. The air filteris used for filtering the intake air of the internal combustion engineof a motor vehicle and is intended to prevent, as thoroughly aspossible, dirt particles or liquid from entering into the intake pipe.

A crankcase ventilation line 71 may be connected to line 1. As a resultof oil expanding in the crankcase of the internal combustion engine, oilfrom the crankcase may continuously enter the line via the crankcaseventilation line in a gaseous form or as fine oil drops. In thiscontext, there is the danger of measuring element 25 becomingcontaminated in an undesired manner by oil particles. When the engine isin operation, the upstream measuring element 25 may only be contaminatedto a small extent, since the oil may not be capable of moving upstreamdue to the high flow velocity of the intake air. When the internalcombustion engine is not in operation, the intake flow is lacking andthe expanding gas-oil mixture of the crankcase may move in everydirection, including towards the measuring element 25, which maycontaminate the measuring element 25.

Line 1 possesses a line wall 2, which has an inner wall 3, with which itencloses flow channel 4, through which the intake air of the internalcombustion engine flows in flow direction 5, which is indicated byarrows. Situated in line 1 is a tubular member 8, which, for example, isaligned in flow direction 5 and runs concentrically with respect tocenter line 7 of pipe 1. Tubular member 8 has a wall 9, whose innerchannel wall 10 bounds a flow-through channel 11 in tubular member 8,through which part of the air drawn in flow direction 5 flows. Tubularmember 8 may be held, for example, by at least two flat, plate-likeshaped braces 12, which extend between inner wall 3 of line 1 and wall 9of tubular member 8, at a right angle to flow direction 5. In additionto holding tubular member 8 in the air flow between line 1 and tubularmember 8, braces 12 cause the pressure drop to increase, which increasesair quantity flowing through flow-through channel 11. Braces 12 alsostraighten the intake-air flow in a desired manner.

The air volume drawn in by the internal combustion engine can berandomly changed by a throttle valve (not shown) situated downstreamfrom tubular member 8, in the intake pipe of the internal combustionengine. A parameter of the flowing gas-liquid mixture to be measured maybe the volume of the gas-liquid mixture flowing per unit time(volumetric flow), e.g., the intake air volume of an internal combustionengine. To ascertain the intake air volume of the internal combustionengine, a measuring body 15 is provided that has an essentially oblong,rectangular design and extends along a longitudinal axis 16.Longitudinal axis 16 runs essentially perpendicularly to center line 7and, as such, perpendicularly to flow direction 5. Measuring body 15 ispartially inserted through a holding opening 17 in line wall 2 andthrough an insertion opening 18 in wall 9 of tubular member 8 andprojects at a measuring end 19 into flow-through channel 11. In thiscontext, a plug end 22 of measuring body 15 for receiving electricalconnections (e.g., plug studs)remains outside of line 1. Insertionopening 18 of tubular member 8 is formed in a first wall segment 23,opposite which, in the direction of longitudinal axis 16, is a secondwall segment 24 of the tubular member 8. Provided in measuring end 19 ofmeasuring body 15 is at least one measuring element 25, which is incontact with the air flowing through flow-through channel 11, and viawhich the air mass drawn in by the internal combustion engine isdetermined. Measuring element 25 may be configured in any availablemanner, e.g., in the form of thermally coupled, temperature-dependentresistors. For example, as referred to in German Published PatentApplication No. 43 38 891, the measuring element 25 may be configured asa micromechanical component part having a dielectric membrane on whichthe resistor elements are formed.

Other parameters of the gas-liquid mixture may be measured. These otherparameters include, but are not limited to, temperature, pressure, andthe like. For this purpose, measuring elements 25 may be designed as inGerman Published Patent No. 42 37 224 or German Published PatentApplication Nos. 43 17 312, 197 11 939, and 197 31 420.

To prevent measuring element 25 from being acted upon in an undesiredmanner by dirt particles or liquid, a first protective element 28 (e.g.,a protective screen 29) is situated at least partially upstream frommeasuring element 25, such as, for example, within flow-through channel11 of tubular member 8. Protective screen 29 may be formed, for example,from plastic and integrated in tubular member 8 or in line 1. This maybe done, for example, by producing protective screen 29 and tubularmember 8 in an injection molding process.

As discussed above, liquids and particles from main flow direction 5travel against the flow direction to reach measuring element 25, such asoccurs when the intake flow is lacking. This backflow is prevented byarranging and using at least one condensation trap 36. For example,condensation trap 36 may be a section of flow channel 4 that is activelycooled, thereby condensing liquids. An element 35, which provides anenlarged inner surface which promotes the condensation of a liquid(e.g., a screen), may also be used as condensation trap 36.

Situated downstream from measuring element 25 in tubular member 8 is aflow straightener 38 of any suitably appropriate construction, whichextends, for example, perpendicularly to flow direction 5 throughflow-through channel 11 of tubular member 8, and which ensures an airflow that is as uniform as possible at and around measuring element 25.In comparison with other flow straighteners, flow straightener 38 foruse as condensation trap 36 may be constructed a bit longer in the flowdirection (e.g. two centimeters) or may include more straightenerchannels 40. Flow straightener 38 includes a plurality of straightenerchannels 40 having inner surfaces 42. These inner surfaces 42 mayprovide a significantly larger condensation surface for the oil vapor oroil moisture than just the existing inner wall channel 10. Also, thecondensation surface may be distributed over the entire flow crosssection of tubular member 8, so that almost no oil passes flowstraightener 38, which may result in significantly less contamination ofmeasuring element 25.

FIG. 2 illustrates another exemplary embodiment of device 50 accordingto the present invention. The same reference numerals are used in thefollowing figure descriptions for identical or equally acting parts.Flow straightener 38, for example, extends beyond tubular member 8 toinner wall 3 of line 2, and includes straightener channels 40 havingdifferent flow cross sections, e.g., in one plane perpendicular tocenter line 7 and parallel to plug axis 16. Straightener channels 40 aredesigned in a region of tubular member 8 such that enlarged condensationsurfaces are available. The width of straightener channels 40, includingopenings 41, is large enough in the region around tubular member 8 sothat the flow should not be noticeably affected. At the same time, flowstraightener 38 can be integrated with tubular member 8 and line wall 2so that flow straightener 38 assumes the function of braces 12.

FIG. 3 illustrates another exemplary embodiment of the device accordingto the present invention. Protective grid 29 extends upstream frommeasuring element 25 and tube member 8, across the entire cross sectionof flow channel 4. Situated at the level of an input opening 61 offlow-through channel 11 of tubular member 8 (i.e., downstream fromprotective grid 29) is at least one second flow straightener 55. In thisembodiment, only one second flow straightener 55 is present. A secondprotective element 58, which is used to reduce the action of liquid orsolid particles on measuring element 25, is integrated, such that itcovers the entire cross section of input opening 61 and abuts directlyagainst input opening 61. Second protective element 58 may be aprotective grid, for example. A protective half-pipe 65 is connectedupstream directly to opening 61 and runs in the axial direction toprotective grid 29. In this context, protective half-pipe 65 is situatedsuch that liquids and solid particles flowing from protective grid 29 toinput opening 61 hit the protective half-pipe's outer surface, so thatthey should not enter tubular member 8 and reach measuring element 25.

FIG. 4 illustrates another exemplary embodiment of the device accordingto the present invention. In contrast to FIG. 3, the protective grid ofFIG. 4 is configured as an additional, second flow straightener 55, inwhich a second protective element 58 is regionally integrated. As viewedfrom main flow direction 5, second protective element 58 covers inputopening 61 of tubular member 8 in an aligned manner.

The exemplary embodiments of FIGS. 3 and 4 should provide asignificantly higher degree of rejection of liquids and solid particlesand guarantee an extended service life of measuring element 25, such asa longer kilometer guarantee of an air volume meter of an internalcombustion engine in a motor vehicle. Measuring body 15, tubular member8, line 1, protective half-ring 65, or flow straightener 38, 55 as wellas additional parts of the device may be made of plastic or metal, forexample.

What is claimed is:
 1. A device for determining at least one parameterof a gas-liquid mixture, the gas-liquid mixture including gas particlesand at least one liquid flowing in an intake air line of an internalcombustion engine, the device comprising: a tubular member extending inthe line and having a flow-through channel; a measuring element situatedin the flow-through channel and around which the gas-liquid mixtureflows; and a condensation trap for trapping the at least one liquid, andbeing situated downstream from the measuring element; wherein thecondensation trap includes a flow straightener; and wherein the flowstraightener occupies the entire cross section of the line, and whereinthe flow straightener includes straightener channels having a smallercross section within a region of the flow-through channel than that ofthe region outside the flow-through channel.
 2. A device for determiningat least one parameter of a gas-liquid mixture, the gas-liquid mixtureincluding gas particles and at least one liquid flowing in an intake airline of an internal combustion engine, the device comprising: a tubularmember extending in the line and having a flow-through channel; ameasuring element situated in the flow-through channel and around whichthe gas-liquid mixture flows; a condensation trap for trapping the atleast one liquid, and being situated downstream from the measuringelement; and at least one protective element situated in the lineupstream from the measuring element, to reduce the action of at leastone of liquid particles and solid particles on the measuring element. 3.The device of claim 2, wherein the at least one protective elementincludes a protective grid located in at least one of the line and thetubular member.
 4. A device for determining at least one parameter of agas-liquid mixture, the gas-liquid mixture including gas particles andat least one liquid flowing in an intake air line of an internalcombustion engine, the device comprising: a tubular member extending inthe line and having a flow-through channel; a measuring element situatedin the flow-through channel and around which the gas-liquid mixtureflows; a condensation trap for trapping the at least one liquid, andbeing situated downstream from the measuring element; and at least oneflow straightener situated in the line upstream from the measuringelement; wherein the flow straightener includes at least one secondprotective element to reduce, within the region of the flow-throughchannel, the action of at least one of liquid particles and of solidparticles on the measuring element.
 5. A device for determining at leastone parameter of a gas-liquid mixture, the gas-liquid mixture includinggas particles and at least one liquid flowing in an intake air line ofan internal combustion engine, the device comprising: a tubular memberextending in the line and having a flow-through channel; a measuringelement situated in the flow-through channel and around which thegas-liquid mixture flows; and a condensation trap for trapping the atleast one liquid, and being situated downstream from the measuringelement; wherein the tubular member includes an input opening in a mainflow direction, and at least one protective half-pipe is providedupstream from the input opening.